Solid-State Transformers Could Help Power the AI Boom

Conventional transformers are a crucial but nearly invisible part of the grid. They move power efficiently across long distances, yet their basic design has changed little in about a century and they are complicated and in short supply. They generally rely on large amounts of specialized steel alloys and miles of copper wire. Their core is typically made of grain-oriented electrical steel, with coils of copper wire on either end; the number of loops in each coil determines whether voltage is stepped up or down. Incoming electricity forms a magnetic field in the core, which induces a voltage on the other side through magnetic induction.

The grid needs transformers because electricity loses some energy as heat while flowing through power lines. Higher voltage and lower current reduce those losses, so power must be stepped up for transmission and stepped down for distribution and use. In the United States, electricity from a solar plant might be converted from direct current to alternating current at about 480 volts, stepped up to 115,000 volts for transmission lines and stepped back down to 120 volts and 240 volts for homes, according to the report. Transformers also often provide galvanic isolation, limiting disturbances and improving safety.

Srdjan Lukic, a professor of electrical and computer engineering at North Carolina State University, told MIT Technology Review that transformers form the backbone of electricity transmission and distribution. He said today’s units are big and bulky and difficult and expensive to replace. Solid-state transformers add power electronics—semiconductors that convert and control electricity—to the conventional blueprint. While a conventional transformer operates at the frequency of the grid section it is connected to, a solid-state transformer controls the frequency of the current.

In a typical solid-state design, incoming alternating current is first converted to direct current and then to higher-frequency alternating current using switches made of a semiconductor such as silicon carbide. A magnetic component then changes the voltage. Because the advanced semiconductors allow greater control over frequency and stability, the magnetic core can be much smaller; some solid-state transformers are roughly one-tenth the size of conventional units with the same capacity, Lukic said. Additional power electronics then convert the electricity from high-frequency alternating current to its required form.

The technology remains under development. Solid-state transformers cannot replace all traditional transformers today, especially the largest ones that work at the high voltages needed for long-distance transmission, according to the report. Still, researchers and companies are looking to modernize transformers as the grid faces growing pressure, and a new generation of the technology could become part of the future grid.

Editor's Summary Solid-state transformers under development add power semiconductors to conventional magnetic designs, offering smaller equipment and more control over power flow. They could help grids handle rising demand from data centers, EVs and other loads, but they cannot yet replace the largest high-voltage transformers. The report says the technology remains a potential part of future grid upgrades rather than a current substitute for all conventional units.